Apparatus for treatment of vertically disposed surfaces

ABSTRACT

A portable airless blasting head suitable for treatment of vertically disposed surfaces is described. The blast head comprises in combination an enclosure with an opening in one side adapted to contact the surface to be treated, projecting means within the enclosure for directing a stream of particulate abrasive material through the opening in the enclosure onto the surface to be treated, a resilient sealing means around the boundary of the opening in the opening of the enclosure which contacts the surface to be treated and retains the abrasive material in the apparatus, and a recirculation means to return the particulate abrasive material to the projecting means. Advantageously the apparatus of the present invention is selfpropelled.

United States Patent [191 Goff [ APPARATUS FOR TREATMENT OF VERTICALLYDISPOSED SURFACES [75] Inventor: James R. Goff, Oklahoma City,

Okla.

[73] Assignee: Robert T. Nelson, Oklahoma City,

Okla.

[22] Filed: Feb. 28, 1972 [21] Appl. No.: 229,842 I Jan. 29, 1974 3/1971Fogle 51/9 [5 7] ABSTRACT A portable airless blasting head suitable fortreatment of vertically disposed surfaces is described. The blast headcomprises in combination an enclosure with an opening in one sideadapted to' contact the surface to be treated, projecting means withinthe enclosure for directing a stream of particulate abrasive materialthrough the opening in the enclosure onto the surface to be treated, aresilient sealing means around the boundary of the opening in theopening of the enclosure which contacts the surface to be treated andretains the abrasive material in the apparatus, and a recirculationmeans to return the particulate abrasive material to the projectingmeans. Advantageously the apparatus of the present invention isself-propelled.

14 Claims, 3 Drawing Figures PATENTEDJAN 29 I974 SHEET 1 OF skrasmoPATENTEDJAH 29 1974 SHEET 2 [1F 2 APPARATUS FOR TREATMENT OF VERTICALLYDISPOSED SURFACES This invention relates to the treatment of verticallydisposed surfaces and more'particularly it pertains to means forcleaning such vertically disposed surfaces with particulate abrasivematerial which is projected at high velocity against the surface to betreated in order to remove rust, dirt, paint and other depositstherefrom. This invention is directed to an apparatus which is mobileand is continuously operable for cleaning surfaces such as metal. Inaddition the novel apparatus is provided with means for recovering theparticulate abrasive material for reuse and means for separating theparticulate abrasive material from dust and other light particles whichresult from the cleaning of the surface.

Heretofore vertically disposed surfaces have com-- monly been airblasted with crushed slag, sand and other abrasives as the abrasive inorder to provide the desired cleaning action. The crushed slagabrasives, sand and other abrasives, however, are subject toconsiderable disintegration and hence no attempts are made for itsrecovery, and the abrasive is simply disposed of after a single use. Airblasting has several other disadvantages. For instance, the compressedair which is required is relatively expensive and contains significantamounts of moisture, and even condensed water, which tend to enhancereoxidation of treated surfaces before protective coatings can beapplied. Additionally, air blasting equipment usually necessitates acrew of three men for the operation of a single head, additional laborand equipment must be used to remove the abrasive and disposal of thelarge amounts of abrasive that is continuously being spent is anadditional consideration. Furthermore, air blasting can be a healthhazard due to'the excessive amounts of dust created, and thus,protective means must be provided to maintain the safety of personnel inthe area surrounding the air blasting operation.

As an alternative, it has been proposed to employ centrifugal blastingwheels to propel the particulate abrasive material. One system having acentrifugal blasting wheel is described in U.S. Pat. No. 3,566,543,issued to Fogel. The patentee discloses a blasting head comprising ahousing, a centrifugal blasing wheel, an

, opening in the housing through which the particulate abrasive isprojected onto the surface to be cleaned, and a pair of resilientsealing members extending continuously around the opening in the housingpositioned so as to effect a seal between the surface to be treated andthe housing. However, several disadvantages exist in the prior artdevice such as the necessity of replacement of the pair of resilientseals which are subject to wearing due to their contact with the surfaceundergoing cleaning, the extensive frame required to support and movethe blast head which substantially reduces its portability, and thenecessity of an operator to be positioned relatively close to the blasthead and thus often expensive safety equipment must be incorporated intothe blast head.

The present invention provides a portable, continuously operable surfacetreating apparatus for the cleaning of vertically disposed surfaces. Thenovel apparatus is economical to manufacture and simply constructed yetsturdy and durable upon extended use and operates with relative freedomfrom wear. Furthermore, the

operation of the apparatus of this invention requires .minimal expensein labor and operating costs. A highly efficient means is provided toprevent loss of particulate abrasive materials and for the isolation ofthe particulate abrasive materials for recycling. Also, means areprovided by the present invention for removal of dust and grit from thesurface undergoing cleaning. Hence, this invention can operate withalmost complete elimination of the passage of grit and dust to theatmosphere and thus can provide a highly acceptable reduction inpollution normally attendant in the use of conventional surface treatingapparatus.

importantly, the highly portable nature of the present invention allowsthe apparatus without concern to geographic location of the verticallydisposed surface to be treated. The apparatus may be employed over roughterrain, water, oil, etc. without the necessity to provide support for aframe external from the surface being treated. An extensive frame is notrequired for its operation. Thus, the apparatus of the present inventionmay be set up for operation quickly and early and its use is notprohibited or restricted by the terrain surrounding the verticallydisposed surface to be treated. The apparatus of this invention isadapted for uniform coverage of surfaces of variable or changingcontour, e.g., vertical curvature as well as horizontal curvature. Theapparatus of the present invention can be operated remotely, addinggreater safety to its operation.

This invention provides a mobile, continuously operable surface treatingapparatus useful for treating vertically disposed surface to be treated,projecting means within the enclosure for directing a stream ofparticulate abrasive material through said opening in the enclosure ontothe surface to be treated, a resilient sealing means on the side of theenclosure having the opening which contacts the surface to be treatedand retains the abrasive material in the enclosure and a recirculationmeans to return the particulate abrasive material to the projectingmeans. The apparatus of the present invention is advantageouslyself-propelled; however, it is also possible to propel the apparatus byother means.

The portable, continuously operable apparatus of the present inventionis generally easily adaptable to numerous uses and is thus broadlypractical and salable. For instance, the apparatus may be used to cleanthe outer side walls of a ships hull, large conservation tanks forwater, gas petroleum or other fluids or solids, walls, exteriors ofbuildings and the like. The material may be metal, concrete or othermaterial where abrasive cleaning may be desired.

For a fuller understanding of the invention, reference should be made tothe following detailed description, taken in connection with theaccompanying drawings, in which:

FIG. 1 is a perspective view of an apparatus of the present invention;

FIG. 2 is a front elevational view with a break away section of theapparatus; and

FIG. 3 is a schematic view of the apparatus in a suitable rigging foroperation to treat a vertically disposed surface.

With reference to FIG. 1, the apparatus, or blast head, is generallyindicated at 10. The blast head 10 comprises an enclosure of housing 12which defines a blast chamber having opening 14 through whichparticulate abrasive material is passed to contact the surface to betreated. Opening 14 also receives rebounding particles from the surfacebeing treated and the scale, deposits or other material being removedfrom the surface. The shape of the opening may be of variousconfigurations. Preferably, the opening is oblong and in an oval orrectangular shape with the major axis of the opening parallel to theprojecting means, for example a centrifugal throwing wheel, located inthe housing and is more preferably at or near perpendicular to thedesired direction of travel of the blast head. When, for example, theapparatus is traveling in a horizontal direction, the major axis of theopening is vertical.

Means are provided to effect a sealing relationship between the surfacebeing treated and the housing. The sealing means is advantageouslydesigned to abate the release of dust, scale or other deposits to theatmosphere at the point of contact with the surface and the loss of theparticulate abrasive materialfrom the housing. The sealing means ispreferably sufficiently resilient to pass over obstructions present onthe surface being treated and to allow sealing over a moderately curvedsurface which is sufficient to prevent release of dust or other materialthrough gaps which would otherwise be formed. The sealing means can beconstructed out of any suitable material such as natural rubbers,synthetic rubbers and other elastomeric materials. For instance,polyurethane elastomerics, butadiene rubbers and the like may beadvantageously employed. The sealing means 16 is depicted as extendingfrom boundary of opening 14, although it may be located in any manner onthe housing which would enable result to be obtained. The sealing meanscan advantageously be of a design which enables easy replacement of thesealing means on the housing. Beneficially, at least the lower portionof the sealing means, that is, the section of the sealing means which ispositioned at the bottom of opening 14 during normal operation of theblasting head, projects angularly, outwardly from the housing in adirection toward the axis perpendicularly extending from the center ofthe plane of the opening. The angular projection of the sealing meansfacilitates the passage to any material deposited thereon to thehousing. Suitable sealing has been observed using a single resilientmember for the sealing means.

The movement of the blast head over the surface to be treated isfacilitated by casters 18 which are mounted on the housing. The castersare rotatably mounted and are affixed to the housing by clamps 20.Clamps 20 permit the casters to be positioned either a greater or lesserdistance from the housing, and the positioning of the casters can bedone manually or remotely. Thus, the working compress upon sealing means16 can easily be adjusted to provide a seal which is sufficient for thenature of the surface being treated. For example, a greater workingcompress will be necessary when treating a rough, irregular surface inorder to abate the escape of dust and the like, whereas a relativelysmooth surface may require a substantially lesser working compress onthe sealing means. Additionally, the casters can be positioned tocontrol the attitude of the apparatus. It is readily seen that by theuse of casters, the use of a complex support frame means to position toapparatus with respect to the surface being treated may not be required.Nor is continual readjustment of the casters necessary to provide asufficient seal with the surface. The casters are shown as beinglaterally positioned on the housing. Other placements of the casters canbe made; for instance, a set of three casters may be employed which areplaced on the housing in a triangular configuration.

As shown in FIG. 1 is fan housing 22. While the fan means is depicted asbeing directly attached to the housing, the fan means may also belocated more distant from the apparatus and employed with, for example,a flexible line, to provide the desired effect. The fan in fan housing22 is designed to draw air in from the chamber formed by housing 12 viavacuum air line 24. The fan draws in air from the chamber which is ladenwith dust and fine particles resulting from the cleaning operation. Theair and materials in association therewith are expelled from the fan toair exhaust duct 26. The fan is powered by a fan motor which iscontained in fan motor housing 28 which is shown as attached to fanhousing 22. The air fed to the chamber in housing 12 is desirablyprovided in association with the particulate abrasive material and iscirculated in the chamber by the projecting means. Desirably, theprojecting means forces air toward the surface being treated and isdrawn upward under the influence of the fan means. The air serves toseparate fines created by the treatment of the surface from heavierparticles such as the particulate abrasive material and larger pieces ofscale or deposit which is removed from the surface. Also, thecirculation of air and its exhaust from the blast head prevents heatbuildup in the abrasive and in the various components of the blast headassembly. The importance of this feature is readily understood when itis realized that large amounts of head are generated by the impact ofthe abrasive against the surface to be treated. Thus, by the circulationof air it becomes possible to operate the apparatus of the presentinvention continously over relatively long periods of time with little,if any, heat buildup in the particulate abrasive material.

If desired, the air exhausted from the blast head via exhaust duct 26can be transmitted to a conventional dust collector (not shown) forremoval of the particulate contaminants in the air. The dust collectorcan be separate from the blast head, in which case, the communicationmeans between exhaust duct 26 and the dust collector is preferablyflexible and allows movement of the blast head over the surface beingtreated. On the other hand, the dust collector may be affixed securelyto the housing of the blast head. The release of dust and the like frombetween the sealing means and the surface being treated can, in part, beabated by operating the apparatus so as to maintain subatmospherepressure, i.e., a pressure lower than ambient, in the chamber.Therefore, if any gap occurs between the sealing means and the surfacebeing treated by reason of, for example, an irregularity on the surfacebeing treated, the atmospheric air, being at the higher pressure, willbe drawn into the chamber at the point of the gap and carrying with itmaterial which-might otherwise escape to the surroundings.

Projection means motor housing 30 is affixed to housing 12. Also shownin FIG. 1 is elevator motor housing 32. The elevator motor thereinpowers a conveyor means which returns the discharged particulateabrasive material to the projecting means to be reused. A motor topropel the blast head in a horizontal direction is provided in drivemotor housing 34. The motor is used to drive horizontal track engagingmeans 36. The slippage between the horizontal track engaging means and ahorizontal track means which is engaged, is avoided through design toprovide friction contact or other essentially non-slipping contact. Thehorizontal track means can be, for example, a cable, rigid or flexibletrack, chain or other suitable device. One particularly advantageousmeans of providing frictional contact of the engaging means 36 to, forexample, a cable is to provide a freely rotable pulley on the opposingside of the cable from the engaging means. The freely rotably pulley canthen be drawn towards the engaging means by, for example, a tensionspring, pneumatic or hydraulic means, or other suitable means to forcethe cable into contact with the engaging means to provide the desired,frictional contact. Desirably, the horizontal tract means is relativelyflexible and positioned such that the track means is bowed with an apexat the engaging means or adjacent to the engaging means. When, forinstance, a cable is employed as the track means, friction suitable fortraction can be achieved be providing a pulley means which can beactivated in a direction essentially perpendicular to the surface beingcleaned to engage the cable and increase the tension in the cable.Suitable activation means are, for instance, a pneumatic or hydrauliccylinder. Beneficially, the pulley and the engaging means can be cablesheaves, each with three grooves. The cable can be threaded on the sidefurthest from the surface being treated of one sheave, across to andaround the second sheave and back to and around the first sheave andacross over the last groove of the second sheave. By increasing thedistance, in any desirable direction, between the pulley and engagingmeans, the tension in the cable can be increased.

Winch means 38 are provided on both sides of the housing 12 andpreferably extend perpendicularly therefrom. The winch means are adaptedfor engaging a vertical support means, which can be, for example, aflexible cable, whereby the vertical support means can be wound on thewinch means to elevate the blast head. The winch means are preferablyinterconnected by a rigid shaft means and is powered by a hoist drivemeans. Desirably, a hoist drive means employed to activate the winchmeans is provided with a self-braking gear drive. The verticallydisposed cable can be supported by a frame means having pulley meansthereon with the cable being attached to housing 12, passed over thepulley means on the frame and back to winch means 38.

FIG. 2 depicts the apparatus of FIG. 1 in a frontelevational view with abreak away section to permit viewing of chamber 40 which is enclosed byhousing 12 and a further break away to permit viewing of the supplymeans to supply particulate abrasive material to the projecting means.Projecting means 42 is represented as a centrifugal throwing wheeldriven by a centrifugal throwing wheel motor in housing 30. A drivemeans 44 can be employed to transmit the power from the motor toprojecting means 42. Projection means 42 can be a conventionalcentrifugal throwing wheel which can be commercially obtained such asthe type manufactured and sold by The Wheelabrator Corporation anddescribed in US. Pat. Nos. 2,708,814 and 2,819,562 or as the typemanufactured and sold by the Pangborn Corporation, a division of theCarborundum Company. In general, the Wheelabrator type wheels comprise aplurality of radially extending blades 43 arranged in circumferentiallyspaced apart relation between confining disc plates. The particulateabrasive material, which can be metallic particles, for example, steelshot, steel grit, crushed iron, chilled iron grit, glass beads, aluminumoxide particles, silica or the like, can be fed into the inner ends ofthe blades, and the particulate abrasive material is throwncentrifugally at high velocity from the outer ends of the blades sincethe wheel is rotated at high speed about its axis, typically at aboutl,000 to 4,000 rpm. The particulate abrasive material is thrown forwardby and through opening 14 into engagement with the surface beingtreated. The abrasive may contact the surface at a slight angle toperpendicular in order to improve the cleaning action.

The particulate abrasive material is stored in storage means 46. Storagemeans 46 is provided with abrasive material transfer means 48 to supplythe abrasive material to projecting means 42. As depicted, the abrasivematerial transfer means is located outside of the housing andcommunicates with the storage means 46 which is depicted as in theinterior of the housing. The abrasive particles flow by gravity throughabrasive material transfer means, shown as a conduit, to a chargingmeans 50 which is shown as a funnel having the large opeining at the topand which is curved in a manner to provide release of the particulateabrasive material to the center of, for example, the centrifugalthrowing wheel. Desirably, the top of the funnel surrounds the lower endabrasive material transfer means 48 and provides a gap sufficient toallow passage of air into the funnel, but yet is preferably designedsuch that the particulate abrasive material does not escape. Thecentrifugal throwing wheel can simultaneously perform as a centrifugalair fan. Thus, during operation, the low pressure area which exists tothe center of the throwing wheel can be employed as a motivational forceto draw in air through the gap formed at the top of the funnel.Additionally, the presence of air being drawn into the center of thethrowing wheel assists the flow of particulate abrasive materials intothe throwing wheel. The air exhausted by the centrifugal throwing wheelcan circulate within the chamber of the housing and desirably flowthrough the particulate abrasive material after impinging upon thesurface being treated so as to wash the abrasive material and removefine particles such as dust and the like. The abrasive material supplymeans may be provided with a valve means or motive 'means to control orfacilitate flow of the particulate abrasive material to the projectingmeans.

The particulate abrasive material, after impinging upon the surfacebeing treated, falls by the force of gravity to the bottom of thechamber formed by housing 12. The spent abrasive material is picked upby particulate abrasive conveyor means 52 to be recycled to theprojecting means 42. Conveyor means 52 is depicted as an endless beltrunning in a clockwise direction on the loop around the inside ofhousing 12; however, other elevator means might be used such aspneumatic lift devices and other conventional mechanical elevators. Theendless belt may employ scoops or bucket means attached thereto atvarious intervals. The drawing depicts several representative scoops 53;however, it is realized that the scoops are spaced at regular intervalson the entire endless belt. When operating the scoop or bucket means isempty on the vertical downpath of the continuous loop. As the beltpasses horizontally through the lower portion of the housing, the scoopitself can be in a vertical collecting position. Continuing its courseon the vertical up path, the scoop or bucket means contains the abrasivematerial. Upon reaching the top of the vertical up path which ispreferably located in the upper portion of the housing, the scoop orbucket passes horizontally across the top, itself in a vertical dumpingposition. The conveyor means, in this delivery zone, releases theparticulate abrasive material to the storage means. The scoops or bucketmeans are preferably below the belt during the lower horizontal pick upflight, and hence, are above the belt during the upper horizontaldumping flight. The scoop or bucket means is essentially free fromcontact which may result in friction caused by wear. Additionally, byemploying a conveyor belt having the scoop or bucket means, less poweris required for its operation then, for example, a pneumatic elevator.The scoop or bucket means can be designed so that a high percentage ofthe particulate abrasive material, often in the neighborhood of 95percent or more falls into storage means 46.

The continuous belt can be a V-belt made of sturdy, flexible materialsuch as synthetic resins or natural rubber. The continuous belt cancontact pulleys 54 at three corners of housing 12 and power pully 56 inthe remaining corner and thus form the configuration, of the continuousloop. Rather than a V-belt and pulley system, the conveyor means maycomprise, for example, a chain and sprocket system wherein the pulleysare replaced by sprockets. Power pulley 56 is depicted as engaging withconveyor means 52 in order to move the conveyor means in a clockwisedirection. Power pulley 56 is driven by elevator motor in housing 32.The elevator motor may be attached to suitable drive means to transmitthe power to power pulley 56. An abrasive collector means may optionallybe provided in the lower portion of housing 12 to assist the recovery ofthe particulate abrasive material. The abrasive collector means may be,for instance, a hopper which is adapted to localize the particulateabrasive material to facilitage its pick up by the conveyor means.

The particulate abrasive material drops from conveyor means into storagemeans 46. Desirably, air which is drawn from chamber 40 to the fan meansin fan housing 22 exits the chamber by a vacuum port means which is incommunication with the fan by means of vacuum air line 24 and which ispreferably located on housing 12 behind the upper horizontal path ofconveyor means 52. The air circulation in chamber 40 can beapproximately diagrammed as follows. Air enters centrifugal throwingwheel 42 and is circulated in a direction towards the surface beingtreated. The air can serve to wash the particulate abrasive material offine particulate matter generated due to the action of the abrasivematerial on the surface. Also, the forced air may serve to dislodgeparticles on the surface that are not removed by the impact of theparticulate abrasive material. The air is then swept upward towards theinlet means carrying with it dust and other fine particulate materialsgenerated in the course of the treatment of the surface. Due to thelocation of the inlet means to the fan, the air passes around theconveyor means. The proximity of the inlet means to the horizontal pathof conveyor means allows the maintenance of relatively high airvelocities past the conveyor means. These higher air velocities canbeneficially be employed to separate particles of a lower specificgravity which are transported by the conveyor from the particulateabrasive material. For instance, when steel shot or the like is used asthe particulate abrasive material, relatively large particles, such asrust or paint, which are not washed from the particulate abrasivematerial by the air circulated by the centrifugal wheel, may becarriedby conveyor means 52 with the steel shot to be returned tostorage means 46. The velocity of air entering the inlet means may,however, be sufficient to remove the relatively large particles of lowerspecific gravity before they enter storage means 46 and essentiallyvacuum the lower density particles from chamber 40. The laden air can beexhausted from the system via the fan and exhaust port 26. Particleswhich may not be removed from the steel shot are normally sufficientlyfragile that upon being propelled by centrifugal throwing wheel 42 andimpacting upon the surface being treated, they disintegrate to aparticle size which. can be readily removed from the system.

Advantageously, storage means 46 can be provided with port 57 throughwhich air in the chamber is drawn and thus the air can be furtherdirected to pass around the conveyor means to insure that the lowdensity particles are swept from the particulate abrasive material. Avalve means can be provided in connection with the port means for vacuumline 24 to adjust the rate of air withdrawal from chamber 40, and hence,the velocity of air over conveyor means 52. An additional vacuum linemay communicate from the fan means to the housing and be adapted tosweep air from other portions of the enclosure.

Motor housing 58 contains a hoist motor to actuate winch means 38 toprovide a means of vertical movement of the blast head. The motor ispreferably attached to a drive means to power shaft 60 which isconnected to winch means 38. As stated previously, the drive means forwinch means 38 is desirably selfbraking.

FIG. 3 illustrates the apparatus to the present invention in connectionwith a suitable rigging means for transporting the apparatus over thesurface being treated. In particular, the surface being treated isindicated as 62 and has thereon a deposit or scale represented by theshaded area. The blast head 10 is positioned upon surface 62 in such amanner that the sealing means contacts the surface to provide arelatively air tight seal. In actual operation, the seal of the sealingmeans with the surface will be broken by, for example, abrupt protusionsor indentations on the surface and thus surrounding air will be drawninto the chamber. Casters 18 contact surface 62 and serve to positionthe blast head a desired distance away from the surface so as to enablethe sealing means to properly contact the surface.

The apparatus is vertically supported by vertical support frame means64. Frame means 64 is depicted as comprising a plurality of supportmembers 66 adapted to support themselves and the blast head whenpositioned at the upper edge of the surface. The frame means canpreferably run along track means 67 which is located adjacent to theupper edge of the surface. Desirably, the track means provides supportfor the frame means for vertical forces, e.g., to counteract gravity,and for a lateral force in a direction perpendicular and away from thesurface. Caster means 68 are provided on the frame means and contact thefront of the surface and reduce friction of movement of the frame meansover the surface. Thus, the frame means will be in equilibrium by itscontact with the track means and the front of the surface and is adaptedto move freely along the edge of the surface. Pulley means 70 are shownas affixed to the upper lateral support members of frame means 64 andare adapted to receive vertical support means 72. The vertical supportmeans attach to housing 12 at attachment means 74 pass over pulley means70 and attach to winch means 38. By drawing more of vertical supportmeans 72 onto winch means 38, the blast head can move in an upwardlydirection, and by releasing a length of vertical support means 72, theblast head can be lowered. Preferably frame supports means 64 isdesigned to enable passage of the blast head at least partially into itsinterior. By locating pulley means 70 to the interior of frame means 64,it is possible to raise the blast head to a position to enable thesealing means to reach or surpass the upper edge of the surface.

The track means which frame means 64 rides upon may be a rail or groovein which wheel means 75, or the like, affixed to frame means can engage.If a rail is employed, the wheel means are preferably designed such thatvertical forces and lateral forces developed by the frame means areconteracted by contact of the wheel means and the track means. The railcan be rigid or somewhat flexible. The track means may be permanentlysecured or may be detachable. Affixing means operable are, for example,vacuum cups, magnets, clamps, or other fastening devices.

Attached to the surface being treated on opposing sides of the blasthead are horizontal track securing means 76. The securing means may bepermanently attached to the surface being treated or it may bedetachable. Attachment means include vacuum cups, magnets, clamps andthe like. Securing means 76 can be in the form of a grooved trackwherein the point of attachment of horizontal track means can be quicklyadjusted to the desired height, either manually or remotely, and evenautomatically. Since the blast head traverses horizontal track means,78, it is often advantageous to maintain about an equal the distancefrom the top edge of the surface to the point track means is secured toeach securing means 76. Thus, for a given vertical position of the blasthead, a horizontal pass may be made, and minimal, if any, concurrentreadjustment of the vertical position need be made. The blast head pullsitself along the horizontal track means by engaging means 36 which isdriven by a horizontal drive motor contained in housing 34. Normally, toaffect engagement of engaging means 36 with the track means to providethe necessary frictional contacts, a tensioning means is provided on theblast head. However, the tension of the track means against the engagingmeans may be increased by shortening the length of track means betweenthe securing means. This can be done by providing, for instance, a winchmeans on one of the securing means. The track means may also be providedwith a turnbuckle means for decreasing its length.

In the operation of an apparatus of the type depicted in the drawings,the frame means 66 is at the upper edge of the surface to be treated andabove the blast head. The vertical support means 72 is attached to theblast head housing, passed over pulley means 70 and attached to winchmeans 38. The winch means is activated and the blast head is elevated tothe desired position. Horizontal track means is then affixed to securingmeans 76 so that it is equidistant from the top edge of the surface andcontacts engaging means 36. The horiat which the zontal drive motor canbe activated to move the blasting head horizontally across the surface.Upon starting the projection means and conveyor means, the treatment ofthe surface commences. The control of the apparatus of the presentinvention can be operated remotely, thus the operator need not beclosely positioned to the blast head. After a horizontal pass, thehorizontal track means can be released from engaging means 36, and theblast head can be raised or lowered to place it in position foradditional passes over the surface. The horizontal track means can berepositioned to engage with the blast head and operation can continue.

While the description of the apparatus has been in terms of travel in ahorizontal direction, it is apparent that the novel apparatus is notlimited to such horizontal operation. For example, the opening in oneside of the enclosure may have its major axis essentially horizontal.Vertical drive can be effected by actuating the winch means. Thehorizontal drive track can be replaced by a vertical tension linepassing from a point above the apparatus to a point below the apparatus.The vertical tension line contacts a freely rotable pulley located onthe housing in a manner which enables the tension line to force theapparatus into contact the surface being treated.

It is claimed:

1. An apparatus for the treatment of surfaces with particulate abrasivematerial which is projected at high velocity against the surfacecomprising;

a. an enclosure in the form of a housing having an I opening in onewall;

b. a projecting means within the enclosure for propelling a stream ofparticulate abrasive material through the opening in the enclosure;

0. a resilient sealing means located on the .wall of the enclosurehaving the opening and being adapted to contact the surface to establisha sealing relation-' ship between the surface and the enclosure;

d. a storage means for the particulate abrasive material which isadapted to supply the projecting means with the particulate abrasivematerial, said storage means defining an upper opening within saidenclosure;

e. a member defining a port in the upper portion of the enclosure fordrawing air from the enclosure, said member being located such that theair from the enclosure is drawn across the opening defined by thestorage hopper to the port; and

f. a recirculation means adapted to collect the propelled particulateabrasive material from a lower portion of the enclosure, to convey thecollected particulate abrasive material to the upper portion of theenclosure, and to deliver the particulate abrasive material at adelivery zone into the storage means, wherein the delivery zone islocated such that the air from the enclosure which is drawn across theopening defined by storage hopper, is drawn across the delivery zone.

2. The apparatus of claim 1 wherein the projecting means is acentrifugal throwing wheel and wherein the centrifugal throwing wheel isadapted to force circulation of air through the opening in the enclosureand toward the surface.

3. The apparatus in claim 1 which is self-propelled and includes thereina hoisting means to propel the apparatus in a vertical direction.

4. The apparatus of claim 3 which includes a horizontal drive means topropel the apparatus in a horizontal direction.

5. The apparatus of claim 1 wherein the opening in the enclosure inoblong and has a major axis which extends vertically and wherein theapparatus moves in a horizontal direction during treatment of thesurface.

6. The apparatus of claim 5 wherein the resilient sealing means in asingle resilient member extending outwardly from the enclosure.

7. The apparatus of claim 1 wherein the vacuum port on the enclosure isin communication with a fan means wherein the fan means is located onthe enclosure.

8. The apparatus of claim 7 wherein the fan means is a centrifugal fan.

9. The apparatus of claim 1 wherein the recirculation means is aconveyor means comprising an endless belt having attached thereon atintervals scoop or bucket means which are adapted to collect theparticulate abrasive material and deliver the particulate abrasivematerial to the storage means.

10. An apparatus for the treatment of surfaces with particulate abrasivematerial which is projected at high velocity against the surfacecomprising:

a. an enclosure in the form of a housing having an opening in one wall;

b. a projecting means within the enclosure for propelling a stream ofparticulate abrasive material through the opening in the enclosure;

c. a resilient sealing means located on the wall of the enclosure havingthe opening and being adapted to contact the surface to establish asealing relationship between the surface and the enclosure;

d. a storage means for the particulate abrasive material which isadapted to supply the projecting means with the particulate abrasivematerial, said storage means defining an upper opening within saidenclosure, said upper opening having a portion which is coterminous witha wall of the enclosure;

e. a member defining a port above the storage hopper in the wall of theenclosure which is coterminous with the upper opening of the storagehopper for drawing air from the enclosure;

f. a recirculation means adapted to collect the propelled particulateabrasive material from a lower portion of the enclosure, to convey thecollected particulate abrasive material to the upper portion of theenclosure, and to deliver the particulate abrasive material at adelivery zone into the storage means, wherein the delivery zone islocated such that the air from the enclosure which is drawn across theopening defined by storage hopper, is drawn across the delivery zone.

1 l. The apparatus of claim 10 wherein the projecting means is acentrifugal throwing wheel and wherein the centrifugal throwing wheel isadapted to force circulation of air through the opening in the enclosureand toward the surface.

12. The apparatus of claim 10 which is self-propelled and includestherein a hoisting means and a horizontal drive means to propel theapparatus in a vertical and a horizontal direction.

13. The apparatus of claim 10 wherein the resilient sealing means is asingle resilient member extending outwardly from the enclosure.

14. The apparatus of claim 10 wherein the recirculation means is aconveyor means comprising an endless belt having attached thereon atintervals scoop or bucket means which are adapted to collect theparticulate abrasive material and deliver the particulate abrasivematerial to the storage means. 1 IF I. l

1. An apparatus for the treatment of surfaces with particulate abrasivematerial which is projected at high velocity against the surfacecomprising; a. an enclosure in the form of a housing having an openingin one wall; b. a projecting means within the enclosure for propelling astream of particulate abrasive material through the opening in theenclosure; c. a resilient sealing means located on the wall of theenclosure having the opening and being adapted to contact the surface toestablish a sealing relationship between the surface and the enclosure;d. a storage means for the particulate abrasive material which isadapted to supply the projecting means with the particulate abrasivematerial, said storage means defining an upper opening within saidenclosure; e. a member defining a port in the upper portion of theenclosure for drawing air from the enclosure, said member being locatedsuch that the air from the enclosure is drawn across the opening definedby the storage hopper to the port; and f. a recirculation means adaptedto collect the propelled particulate abrasive material from a lowerportion of the enclosure, to convey the collected particulate abrasivematerial to the upper portion of the enclosure, and to deliver theparticulate abrasive material at a delivery zone into the storage means,wherein the delivery zone is located such that the air from theenclosure which is drawn across the opening defined by storage hopper,is drawn across the delivery zone.
 2. The apparatus of claim 1 whereinthe projecting means is a centrifugal throWing wheel and wherein thecentrifugal throwing wheel is adapted to force circulation of airthrough the opening in the enclosure and toward the surface.
 3. Theapparatus in claim 1 which is self-propelled and includes therein ahoisting means to propel the apparatus in a vertical direction.
 4. Theapparatus of claim 3 which includes a horizontal drive means to propelthe apparatus in a horizontal direction.
 5. The apparatus of claim 1wherein the opening in the enclosure in oblong and has a major axiswhich extends vertically and wherein the apparatus moves in a horizontaldirection during treatment of the surface.
 6. The apparatus of claim 5wherein the resilient sealing means in a single resilient memberextending outwardly from the enclosure.
 7. The apparatus of claim 1wherein the vacuum port on the enclosure is in communication with a fanmeans wherein the fan means is located on the enclosure.
 8. Theapparatus of claim 7 wherein the fan means is a centrifugal fan.
 9. Theapparatus of claim 1 wherein the recirculation means is a conveyor meanscomprising an endless belt having attached thereon at intervals scoop orbucket means which are adapted to collect the particulate abrasivematerial and deliver the particulate abrasive material to the storagemeans.
 10. An apparatus for the treatment of surfaces with particulateabrasive material which is projected at high velocity against thesurface comprising: a. an enclosure in the form of a housing having anopening in one wall; b. a projecting means within the enclosure forpropelling a stream of particulate abrasive material through the openingin the enclosure; c. a resilient sealing means located on the wall ofthe enclosure having the opening and being adapted to contact thesurface to establish a sealing relationship between the surface and theenclosure; d. a storage means for the particulate abrasive materialwhich is adapted to supply the projecting means with the particulateabrasive material, said storage means defining an upper opening withinsaid enclosure, said upper opening having a portion which is coterminouswith a wall of the enclosure; e. a member defining a port above thestorage hopper in the wall of the enclosure which is coterminous withthe upper opening of the storage hopper for drawing air from theenclosure; f. a recirculation means adapted to collect the propelledparticulate abrasive material from a lower portion of the enclosure, toconvey the collected particulate abrasive material to the upper portionof the enclosure, and to deliver the particulate abrasive material at adelivery zone into the storage means, wherein the delivery zone islocated such that the air from the enclosure which is drawn across theopening defined by storage hopper, is drawn across the delivery zone.11. The apparatus of claim 10 wherein the projecting means is acentrifugal throwing wheel and wherein the centrifugal throwing wheel isadapted to force circulation of air through the opening in the enclosureand toward the surface.
 12. The apparatus of claim 10 which isself-propelled and includes therein a hoisting means and a horizontaldrive means to propel the apparatus in a vertical and a horizontaldirection.
 13. The apparatus of claim 10 wherein the resilient sealingmeans is a single resilient member extending outwardly from theenclosure.
 14. The apparatus of claim 10 wherein the recirculation meansis a conveyor means comprising an endless belt having attached thereonat intervals scoop or bucket means which are adapted to collect theparticulate abrasive material and deliver the particulate abrasivematerial to the storage means.